Public bug reported: When hyper threading is enabled, the way emulator_threads_policy allocates the extra cpu resource for emulator is not optimal.
The instance I use for testing is a 6-vcpu VM; before enable this emulator_threads_policy, I reserve 6 cpu (actually 6 threads since we enable hyper threading) in nova config, vcpu_pin_set=8,10,12,32,34,36 Now when we enable emulator_threads_policy, in stead of adding one more thread to this vcpu pin list in the nova config, I end up adding two more sibling threads (on the same core) vcpu_pin_set=8,10,12,16,32,34,36,40 So I ended up using 2 more threads, but only of them is used for emulator and the other thread is wasted. Originally reported on Bugzilla - https://bugzilla.redhat.com/1534669 ** Affects: nova Importance: Undecided Status: New ** Description changed: When hyper threading is enabled, the way emulator_threads_policy allocates the extra cpu resource for emulator is not optimal. - The instance I use for testing is a 6-vcpu VM; before enable this emulator_threads_policy, I reserve 6 cpu (actually 6 threads since we enable hyper threading) in nova config, - vcpu_pin_set=8,10,12,32,34,36 + The instance I use for testing is a 6-vcpu VM; before enable this + emulator_threads_policy, I reserve 6 cpu (actually 6 threads since we + enable hyper threading) in nova config, - Now when we enable emulator_threads_policy, in stead of adding one more thread to this vcpu pin list in the nova config, I end up adding two more sibling threads (on the same core) - vcpu_pin_set=8,10,12,16,32,34,36,40 + vcpu_pin_set=8,10,12,32,34,36 + + Now when we enable emulator_threads_policy, in stead of adding one more + thread to this vcpu pin list in the nova config, I end up adding two + more sibling threads (on the same core) + + vcpu_pin_set=8,10,12,16,32,34,36,40 So I ended up using 2 more threads, but only of them is used for emulator and the other thread is wasted. Originally reported on Bugzilla - https://bugzilla.redhat.com/534669 ** Description changed: When hyper threading is enabled, the way emulator_threads_policy allocates the extra cpu resource for emulator is not optimal. The instance I use for testing is a 6-vcpu VM; before enable this emulator_threads_policy, I reserve 6 cpu (actually 6 threads since we enable hyper threading) in nova config, - vcpu_pin_set=8,10,12,32,34,36 + vcpu_pin_set=8,10,12,32,34,36 Now when we enable emulator_threads_policy, in stead of adding one more thread to this vcpu pin list in the nova config, I end up adding two more sibling threads (on the same core) vcpu_pin_set=8,10,12,16,32,34,36,40 So I ended up using 2 more threads, but only of them is used for emulator and the other thread is wasted. - Originally reported on Bugzilla - https://bugzilla.redhat.com/534669 + Originally reported on Bugzilla - https://bugzilla.redhat.com/1534669 -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to OpenStack Compute (nova). https://bugs.launchpad.net/bugs/1744965 Title: 'emulator_threads_policy' doesn't work with 'vcpu_pin_set' Status in OpenStack Compute (nova): New Bug description: When hyper threading is enabled, the way emulator_threads_policy allocates the extra cpu resource for emulator is not optimal. The instance I use for testing is a 6-vcpu VM; before enable this emulator_threads_policy, I reserve 6 cpu (actually 6 threads since we enable hyper threading) in nova config, vcpu_pin_set=8,10,12,32,34,36 Now when we enable emulator_threads_policy, in stead of adding one more thread to this vcpu pin list in the nova config, I end up adding two more sibling threads (on the same core) vcpu_pin_set=8,10,12,16,32,34,36,40 So I ended up using 2 more threads, but only of them is used for emulator and the other thread is wasted. Originally reported on Bugzilla - https://bugzilla.redhat.com/1534669 To manage notifications about this bug go to: https://bugs.launchpad.net/nova/+bug/1744965/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : [email protected] Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
